As the homologous series of normal alcohols is ascended from ethanol, CNS depressant potency increases up to eight carbon atoms, with activity decreasing thereafter. Branching of the alkyl chain increases depressant activity and, in an isometric series, the order of potency is tertiary > secondary > primary. In part, this may be because tertiary and secondary alcohols are not metabolized by oxidation to the corresponding carboxylic acids. Replacement of a hydrogen atom in the alkyl group by a halogen increases the alkyl portion and, accordingly, for the lower-molecular weight compounds, increases potency. Carbamylation of alcohols generally increases depressant potency. Carbamate groups are generally much more resistant to metabolic inactivation than hydroxyl functions. Most of the alcohols and carbamates have been superseded as sedative-hypnotics. Several difunctional compounds (e.g., diol carbamates) have depressant action on the cord in addition to the brain and are retained principally for their skeletal muscle relaxant properties.
Ethchlorvynol, USP. Ethchlorvynol, 1-chloro-3-ethyl-1-penten-4-yn-3-ol (Placidyl), is a mild sedative-hypnotic with a quick onset and short duration of action (ty2 = 5.6 hours). Because of its highly lipophilic character, it is extensively metabolized to its secondary alcohol (~90%) prior to its excretion. It reportedly induces microsomal hepatic enzymes. Acute overdose shares several features with barbiturate overdose.
Meprobamate, USP. Meprobamate, 2-methyl-2-propyltrimethylene dicarbamate, 2-methyl-2-propyl-1,3-propanediol dicarbamate (Equanil, Miltown), is officially indicated as an antianxiety agent. It is also a sedative-hypnotic agent. It has several overall pharmacological
properties resembling those of benzodiazepines and barbiturates. The mechanism of action underlying anxiolytic effects is unknown but may involve effects on conductivity in specific brain areas.19 It does not appear to act through effects on GABAergic systems. The drug is effective against absence seizures and may worsen generalized tonic-clonic seizures.
Meprobamate is also a centrally acting skeletal muscle relaxant. The agents in this group find use in several conditions, such as strains and sprains that may produce acute muscle spasm. They have interneuronal blocking properties at the level of the spinal cord, which are said to be partly responsible for skeletal muscle relaxation.19 Also, the general CNS depressant properties they possess may contribute to, or be mainly responsible for, the skeletal muscle relaxant activity. Dihydric compounds and their carbamate (urethane) derivatives, as described previously in the discussion of meprobamate, are prominent members of the group.
Was this article helpful?
Stop Letting Anxiety Rule Your Life And Take Back The Control You Desire Right Now! You don't have to keep letting your anxiety disorder run your life. You can take back your inner power and change your life for the better starting today! In order to have control of a thing, you first must understand it. And that is what this handy little guide will help you do. Understand this illness for what it is. And, what it isn't.